JP3627419B2 - Engine air-fuel ratio control device - Google Patents

Description

の式で与えられる有効パルス幅Ｔｅｎが次のｔ９の時点での同期噴射に使われる。
【００８２】
▲９▼ｔ９の時点：ｔ９は同期噴射のタイミングで、このときｔ８のタイミングで演算された上記（ｉｉ）式のＴｅｎで同期噴射が行われる（オ参照）。（ｉｉ）式において、Ｅ１は１回目の非同期噴射における噴き過ぎ分、Ｅ２は２回目の非同期噴射における噴き過ぎ分、Ｅ３は３回目の非同期噴射における噴き過ぎ分であり、これらの噴き過ぎ分（つまりＥ１＋Ｅ２＋Ｅ３）を、非同期噴射の終了した直後に訪れる同期噴射タイミングで、その同期噴射量（Ａｖｔｐ）から減量するのである。このようにして同期噴射量を減量補正した後は、次回の非同期噴射に備えるためＥＲＡＣＩｎ＝０とされる。
【００８３】
１０ｔ１０の時点：Ｃｈｏｓｎ（＝０）とＴｅｎが演算される。ＥＲＡＣＩｎについては、ＥＲＡＣＩｎ＝０である。
【００８４】
このようにして、非同期噴射とその直後の第１回目の同期噴射が行われるとき、急加速の前後で各気筒とも空燃比を理論空燃比へと制御できるのである。
【００８５】
次に、図１１のフローチャートはフュエルリカバー条件の判定を行うための、また図１２のフローチャートはフュエルリカバー条件の終了判定を行うためのもので、図２、図４、図１６とは独立に一定時間毎に実行する。なお、図１１のフローに続けて図１２のフローを実行する。
【００８６】
まず、図１１のほうから説明すると、ステップ４１ではフュエルカット時かどうかみて、フュエルカット時のときだけステップ４２以降に進む。
【００８７】
ステップ４２、４３、４４では次の条件、
〈１〉車速ＶＳＰが所定値（たとえば８ｋｍ／ｈ）以下のとき、
〈２〉アイドルスイッチがＯＦＦとなったとき、
〈３〉自動変速機付き車両では回転数Ｎが所定値以下（たとえば冷却水温に応じた所定値以下または２０００ｒｐｍ以下）となったとき
であるかどうかを１つずつチェックし、いずれかの条件も満たさないときはステップ４５に進んでフラグＦＲＣに“０”を入れ、いずれかの条件でも満たすとき（フュエルリカバー条件の成立時）はステップ４６、４７でフラグＦＲＣに“１”をセットし、かつフラグＦＦＣに“０”をリセットする。
【００８８】
図１２に移り、ステップ５１ではフュエルリカバー時であるかどうかをフラグＦＲＣにより判断し、ＦＲＣ＝１のとき（フュエルリカバー時）はステップ５２でカウンタＣＮＴｎをみて、全気筒でカウンタＣＮＴｎが１となっているときは、ステップ５３に進んでフラグＦＲＣに“０”をリセットし、次回のフュエルリカバー制御のためステップ５４においてカウンタＣＮＴｎをすべての気筒について０にリセットする。つまり、フュエルリカバーの開始より各気筒で１回の噴射（同期噴射または割込み噴射）が終わったタイミングでフュエルリカバーを終了する。
【００８９】
フュエルリカバー時に噴射がどのように行われるかを上記の特定気筒について簡単に示すと、図１３のように、フュエルリカバーの開始タイミングでのΔＡｖｔｐｎがＬＡＳＮＩを超えるときは、そのΔＡｖｔｐｎを用いてＩｎｊｓｅｔｎ、ＥＲＡＣＩｎが計算され、フュエルリカバー開始後に非同期噴射が行われるとともに、非同期噴射が終了した直後の第１回目の同期噴射タイミングでだけ、同期噴射量からＥＲＡＣＩｎの分が減量される。なお、フュエルリカバー時の非同期噴射は、フュエルカット中に同期噴射タイミングとなり、かつ吸気行程のあいだにフュエルリカバー信号が入った気筒から開始する。一方、フュエルリカバーの開始タイミングでのΔＡｖｔｐｎがＬＡＳＮＩ以下のときは、そのΔＡｖｔｐｎを用いてＣｈｏｓｎが計算され、フュエルリカバー開始後の同期噴射タイミングで、Ｃｈｏｓｎの加わった同期噴射量が気筒別に供給される。
【００９０】
以上で特開平３−１１１６３９号公報の概説と、フュエルカット時、フュエルリカバー時の制御の説明を終える。
【００９１】
さて、自動変速機を備える車両においてフュエルカット状態から▲１▼アクセルペダルを踏み込むことなく車速が低下して所定値以下となったときや▲２▼再加速を行おうとアクセルペダルを踏み込んだときに、いわゆるフュエルリカバーが行われるのであるが、上記のように壁流補正を行うものでは、フュエルカット時の壁流燃料の減少に合わせて壁流燃料を予測することで、フュエルリカバー時にフュエルカット時における壁流燃料の消失分だけ多めに増量することが可能となり、フュエルリカバー当初の空燃比を理論空燃比に近づけることができることから、図１６第４段目に示すように、フュエルリカバー時にエンジン発生トルクがステップ的に立ち上がる。
【００９２】
この場合に、上記▲１▼と▲２▼ではトルク要求が異なることから、現状では▲２▼の場合のフュエルリカバー時に図１６第１段目の実線で示したように壁流補正を行うものの、▲１▼の場合のフュエルリカバー時には、図１６第１段目の破線のように壁流補正を行っていない。▲２▼の場合のフュエルリカバー時には壁流補正によりエンジンの発生するトルクがステップ的に立ち上がって（図１６第３段目の実線参照）、加速要求に応じたものとなるのに対して、▲１▼の場合のフュエルリカバー時にはエンジン発生トルクがゆるやかに立ち上がり（図１６第３段目の破線参照）、トルクショックを低減するのである。なお、壁流補正ありのときの燃料噴射パルス幅Ｔｉｎの波形（図１６第１段目の実線）はモデル的に表したもので、実際には図１３の最下段に示したようになる。
【００９３】
しかしながら、▲１▼の場合でアクセルペダルを踏み込むことなく車速が低下するといっても、車速（エンジン回転数）の低下は一様でなく、たとえば緩減速のほか急減速時があり、急減速からのフュエルリカバー時にも、上記▲１▼の場合のフュエルリカバー時と同じにトルクをゆるやかに立ち上げたのでは、急減速時の急減な回転落ちからの回復が遅れ、エンストに至ることが考えられる。
【００９４】
これに対処するため参考例では、現状と相違して〈１〉の場合のフュエルリカバー時（アイドルスイッチがＯＮ状態でのフュエルリカバーの場合）にも壁流補正を行うとともに、そのフュエルリカバー開始時の所定時間当たりエンジン回転数減少量に応じてそのフュエルリカバー時のエンジン発生トルクを新たに制御する。
【００９５】
詳細には、図２のステップ６、９に示したように、フュエルリカバー時ゲインＫＧＺ１を新たに導入し、上記の（３）、（４）、（６）式に代えて、

の式により気筒別増減補正量Ｃｈｏｓｎ、気筒別非同期噴射パルス幅Ｉｎｊｓｅｔｎを計算する。
【００９６】
ただし、気筒別噴き過ぎ補正量ＥＲＡＣＩｎの式に対してはＫＧＺ１を導入しない（つまり従来のまま）。
【００９７】
（１１）、（１２）、（１３）式のＫＧＺ１の演算については図１４のフローチャートにより説明する。図１４のフローチャートは図２よりも先に一定時間毎に実行する。
【００９８】
ステップ６１、６２では、今回フュエルリカバー時であるかどうか、アイドルスイッチがＯＦＦかどうかみる。今回フュエルリカバー時でありアイドルスイッチがＯＮのときはステップ６３に進み、前回はフュエルリカバー時であったかどうかみる。
【００９９】
前回はフュエルリカバー時でなかった（つまりフュエルカットからフュエルリカバーへの切換時）は、ステップ６４に進み、
ΔＮ＝Ｎ（ｏｌｄ）−Ｎ …（１４）
ただし、Ｎ（ｏｌｄ）：Ｎの前回値
の式によりフュエルリカバーの開始タイミングにおける所定時間当たりの回転数減少量ΔＮ［ｒｐｍ／ｍｓ］を計算し、このΔＮよりステップ６５において図１５を内容とするテーブルを参照してフュエルリカバー時ゲインＫＧＺ１［無名数］を求める。ＫＧＺ１は図１５のように、ΔＮが小さいとき（つまり緩減速時）は負の値に、これに対してΔＮが大きいとき（つまり急減速時）は０となる値である。
【０１００】
ステップ６６では次回制御のためＮの値をメモリΔＮ（ｏｌｄ）に移したあと、図１４のフローを終了する。
【０１０１】
一方、フュエルリカバー時でないときやフュエルリカバー時でもアイドルスイッチがＯＦＦのときはＫＧＺ１が不要であるため、ステップ６１、６２よりステップ６７に進み、ＫＧＺ１に０を入れ、ステップ６６の操作を実行したあと図１４のフローを終了する。アイドルスイッチがＯＮ状態でフュエルリカバー時が継続しているときはステップ６３よりステップ６４、６５を飛ばしてステップ６６の操作を実行する。
【０１０２】
このようにして演算されるＫＧＺ１を、上記の（１１）、（１２）、（１３）式で用いると、フュエルリカバーの開始タイミングにおける所定時間当たりの回転数減少量ΔＮが小さいとき（緩減速時）はＣｈｏｓｎ、Ｉｎｊｓｅｔｎが減量補正され、これに対してΔＮが大きいとき（急減速時）のＣｈｏｓｎ、Ｉｎｊｓｅｔｎは従来と同じである。
【０１０３】
ただし、（１１）式においてＧｚｔｗｐ＋ＫＧＺ１は、Ｇｚｔｗｐ＋ＫＧＺ１≧０に制限する。このように制限するのは次の理由による。Ｃｈｏｓｎのもともとの構成において、ΔＡｖｔｐｎの正負によりＣｈｏｓｎを増量分として加えるか減量分として加えるかを決定している。これに対してＧｚｔｗｐはゲインを定めるだけの値であるから、Ｇｚｔｗｐ≧０である。本発明ではＫＧＺ１が負の値で加わることがあるので（図１５参照）、Ｇｚｔｗｍ＋ＫＧＺ１＜０となってしまったのでは、ΔＡｖｔｐｎの正負によってはＣｈｏｓｎを増量分として加えるか減量分として加えるかを決定できなくなる。そこで、Ｇｚｔｗｐ＋ＫＧＺ１≧０とすることで、Ｃｈｏｓｎのもともとの構成が保持されるようにしたのである。同じ理由から（１２）式ではＧｚｔｗｍ＋ＫＧＺ１をＧｚｔｗｍ＋ＫＧＺ１≧０に、また（１３）式ではＧｚｔｗ×Ｇｚｃｙｌ＋ＫＧＺ１をＧｚｔｗ×Ｇｚｃｙｌ＋ＫＧＺ１≧０に制限する。
【０１０４】
ここで、参考例の作用を説明する。
【０１０５】
過渡補正量Ｋａｔｈｏｓに加えて、上記の（３）、（６）式のＣｈｏｓｎとＩｎｊｓｅｔｎを用いて燃料噴射制御を行うものでは、フュエルカット時の壁流燃料の減少に合わせて壁流燃料を予測することで、フュエルリカバー時にフュエルカット時における壁流燃料の消失分だけ多めに増量することが可能となり、フュエルリカバー当初の空燃比を理論空燃比に近づけることができることからフュエルリカバー時にエンジン発生トルクがステップ的に立ち上がるのであるが（図１６第４段目参照）、▲１▼アクセルペダルを踏み込むことなく車速が低下して所定値以下となったときのフュエルリカバー時と▲２▼再加速を行おうとアクセルペダルを踏み込んだときのフュエルリカバー時とではトルク要求が異なることから、現状では▲１▼の場合のフュエルリカバー時に限り壁流補正を行わないことで（図１６第３段目線参照）、エンジン発生トルクをゆるやかに立ち上げ、トルクショックを低減している。しかしながら、上記▲１▼の場合でアクセルペダルを踏み込むことなく車速が低下するといっても、車速（エンジン回転数）の低下は一様でなく、たとえば緩減速のほか急減速時があり、急減速からのフュエルリカバー時にも、上記▲１▼の場合のフュエルリカバー時と同じにトルクをゆるやかに立ち上げたのでは、急減速時の急減な回転落ちからの回復が遅れ、エンストに至ることが考えられることを前述した。
【０１０６】
これに対して参考例では、現状と相違してアイドルスイッチがＯＮ状態でのフュエルリカバーの場合にも壁流補正を行い、かつそのフュエルリカバーの開始タイミングでの所定時間当たり回転数減少量ΔＮに応じたゲインＫＧＺ１を新たに導入しており、アイドルスイッチがＯＮ状態でのフュエルリカバーのうち急減速時からのフュエルリカバー時（つまりΔＮが大のとき）にはＫＧＺ１＝０としている。このときは、図１６第５段目の実線で示すトルク特性となり、急減速からのフュエルリカバー時に急激なトルク増加が生じるため、急減速時の急減な回転落ちを避けることができる。
【０１０７】
その一方で、アイドルスイッチがＯＮ状態でのフュエルリカバーの場合でありながら、緩減速からのフュエルリカバー時にはＫＧＺ１に負の値を与えることにより、上記（１１）式のＣｈｏｓｎ、上記（１３）式のＩｎｊｓｅｔｎがそれぞれ減量修正される。つまり、緩減速からのフュエルリカバー時にはＣｈｏｓｎ、Ｉｎｊｓｅｔｎがともに通常の加速時より減少することから、その減少分だけフュエルリカバー時のトルク増加が滑らかになるのである（図１６第５段目の破線参照）。
【０１０８】
なお、図１６第５段目の破線で示したように、緩減速からのフュエルリカバー時（図ではΔＮが小のとき）のトルクが階段状に大きくなっているのは、各気筒の燃焼毎にトルクが発生することに対応させたものである。図１６第５段目の破線特性では、３気筒分の燃焼で実線と一致しているが、いくつの気筒分の燃焼で実線と一致するかどうかはフュエルリカバー時ゲインＫＧＺ１により定まる。気筒数はいくつの気筒分の燃焼で実線と一致するかどうかに関係しない。
【０１０９】
このようにして、参考例では、アイドルスイッチがＯＮ状態でのフュエルリカバーの場合にも応答の遅い壁流燃料と応答の速い壁流燃料をともに対象とする壁流補正を行い、かつフュエルリカバー時ゲインＫＧＺ１（つまりΔＮ）に応じてエンジン発生トルクを制御するので、アイドルスイッチがＯＮ状態でのフュエルリカバーの場合のトルク特性が図１６第５段目のようになり、アイドルスイッチがＯＮ状態でのフュエルリカバーの場合においても、急減速からの急減な回転落ちを避けることができるとともに緩減速からのフュエルリカバー時のトルクショックを回避できるのである。
【０１１０】
図１７のフローチャートは本発明の第１実施形態で、参考例の図１４に対応する。なお、図１４と同一の部分には同一のステップ番号をつけている。
【０１１１】
エンジンと自動変速機を直結状態とする、いわゆるロックアップ機構が自動変速機に備えられるのものにおいて、エンジンと自動変速機が直結されている状態（ロックアップ領域）でアイドルスイッチがＯＮ状態でのフュエルリカバーを行ったのでは、自動変速機負荷の分だけエンジン回転の上昇が遅れるので、アイドルスイッチがＯＮ状態でのフュエルリカバーを行う前にロックアップ解除信号を出力しているのであるが、ロックアップ解除信号を与えてからロックアップ機構の作動が実際に解除されるまでの応答遅れにより、アイドルスイッチがＯＮ状態でのフュエルリカバーの開始タイミングでエンジンと自動変速機とが直結状態のことがある（図１９参照）。つまり、アイドルスイッチがＯＮ状態でのフュエルリカバーの場合において、急減速からのフュエルリカバー時かつロックアップ機構の作動遅れによりエンジンと自動変速機とが直結状態にあるときには、急激な回転落ちがとまらず、エンストに至ることが考えられる。
【０１１２】
そこで、第１実施形態では、アイドルスイッチがＯＮ状態でのフュエルリカバーのうち、急減速からのフュエルリカバー時かつロックアップ領域のとき、急減速からのフュエルリカバー時かつロックアップ領域でないときよりもエンジン発生トルクが増す側にＣｈｏｓｎ、Ｉｎｊｓｅｔｎを修正する。
【０１１３】
具体的には、図１７においてステップ７１、７２が図１４の参考例と異なっている。ステップ７１ではロックアップ領域にあるかどうかをフラグＦＬＵにより判断する。フラグＦＬＵ＝１のときはロックアップ領域にあると判断し、ステップ７２でΔＮより図１８の一点鎖線を内容とするテーブルを参照して、フュエルリカバー時ゲインＫＧＺ２を求め、これをステップ７３において、ＫＧＺ１に入れる。フラグＦＬＵ＝０のとき（ロックアップ領域にないとき）は、参考例と同様にステップ７１よりステップ６５に進み、ΔＮより図１８の実線を内容とするテーブルを参照してＫＧＺ１を求める。
【０１１４】
この実施形態では、図１８に示したように、アイドルスイッチがＯＮ状態でのフュエルリカバーのうち、急減速時からのフュエルリカバーに際して（図ではΔＮが大きいとき）、ロックアップ領域にあるときＫＧＺ１（＝ＫＧＺ２）が正の値で与えられ、ロックアップ状態にないときよりもこの正の分だけＣｈｏｓｎ、Ｉｎｊｓｅｔｎが増量修正されることから、このときのトルク特性を図１６第５段目に重ねて示すと、２点鎖線のようになる。つまり、アイドルスイッチがＯＮ状態でのフュエルリカバーのうち、急減速時からのフュエルリカバーの開始タイミングでエンジンと自動変速機とが実際には直結状態にとどまることがあり、このときエンジンに対して自動変速機分が負荷増加となるのに対応して、ＫＧＺ１によりその負荷増加分のトルク増加を行っているのであり、これによって、ロックアップ解除信号を与えてからロックアップ機構の作動が実際に解除されるまでの応答遅れにより、アイドルスイッチがＯＮ状態でのフュエルリカバーのうち、急減速時からのフュエルリカバーの開始タイミングでエンジンと自動変速機とが直結状態にあることがあっても、急激な回転落ちに伴うエンストを防止することができる。
【０１１５】
なお、自動変速機がロックアップ領域にあるかどうかの判定は、実際には自動変速機用コントロールユニット（図示しない）の側で実行し、その判定結果を通信装置を介してエンジン制御用コントロールユニット２０に送信するようにしている。
【０１１６】
たとえば、自動変速機用コントロールユニットでは図２０のフローチャートにしたがって、ロックアップ領域かどうかの判定を行っている。ロックアップ領域は図２１に示したように、絞り弁開度ＴＶＯと車速ＶＳＰをパラメータとするマップ上で与えており、そのときのＴＶＯとＶＳＰがロックアップ領域にあれば、ステップ７１よりステップ７２に進んで、ロックアップソレノイド（図示しない）にＯＮ信号（ロックアップ信号）を出力し、ロックアップ領域でないときはステップ７１よりステップ７４に進んで、ＯＦＦ信号（ロックアップ解除信号）をロックアップソレノイドに出力する。
【０１１７】
なお、フュエルリカバーを行う前にロックアップ解除信号が出力されるように、フュエルリカバーの開始タイミングでの車速よりもロックアップ解除信号を出力するときの車速（この車速が図２１に示す４０ｋｍ／ｈ）のほうを高くしている。
【０１１８】
また、ロックアップ信号を出力するときはステップ７３でフラグＦＬＵを“１”にセットし、ロックアップ解除信号を出力するときはステップ７５においてＦＬＵを“０”にリセットする。このフラグＦＬＵの値をエンジン制御用コントロールユニット２０に送信するのである。
【０１１９】
参考例の図１８ではＫＧＺ１が−０．７５、−０．２５、０の３段階で示したが、これに限られるものでなく、段階の数をさらに増やしてもかまわない。また、飛び飛びの値（不連続値）とすることも必要でなく、連続値でもかまわない。
【０１２０】
参考例ではＫＧＺ１≦０の場合で説明したが、要求があれば、第１実施形態と同様にＫＧＺ１に正の値を与えることで、トルク増加を行うこともできる。
【０１２１】
実施形態では３つのゲインＧｚｔｗ、Ｇｚｔｗｐ、Ｇｚｔｗｍが冷却水温Ｔｗに応じた値である場合で説明したが、冷却水温に限られるものでなく、壁流付着部温度を予測し、この予測温度に応じて３つのゲインＧｚｔｗ、Ｇｚｔｗｐ、Ｇｚｔｗｍを求めるようにしたものに対しても本発明を適用できる。
【０１２２】
実施形態では応答の遅い壁流燃料に関する補正量と応答の速い壁流燃料に関する補正量を導入するもので説明したが、壁流燃料に関する補正量はこれに限定されるものでなく、他の公知の壁流燃料を行うものに対しても本発明を適用する事が可能である。
【図面の簡単な説明】
【図１】第１実施形態の制御システム図である。
【図２】気筒別燃料噴射パルス幅Ｔｉｎの演算を説明するためのフローチャートである。
【図３】噴射タイミングと冷却水温に対する直接率Ｚの特性図である。
【図４】３つのゲインＧｚｔｗ、Ｇｚｔｗｐ、Ｇｚｔｗｍの演算を説明するためのフローチャートである。
【図５】気筒別非同期噴射ゲインＧｚｔｗの特性図である。
【図６】気筒別増量ゲインＧｚｔｗｐの特性図である。
【図７】気筒別減量ゲインＧｚｔｗｍの特性図である。
【図８】噴射タイミング毎に実行するフローチャートである。
【図９】緩加速時について壁流燃料のうちの高周波成分を対象とする壁流補正を説明するための波形図である。
【図１０】急加速時について壁流燃料のうちの高周波成分を対象とする壁流補正を説明するための波形図である。
【図１１】フュエルリカバー条件の判定を説明するためのフローチャートである。
【図１２】フュエルリカバー条件の終了判定を説明するためのフローチャートである。
【図１３】フュエルリカバー時について壁流燃料のうちの高周波成分を対象とする壁流補正を説明するための波形図である。
【図１４】フュエルリカバー時ゲインＫＧＺ１の演算を説明するためのフローチャートである。
【図１５】フュエルリカバー時ゲインＫＧＺ１の特性図である。
【図１６】従来装置の作用とともに参考例の作用を説明するための波形図である。
【図１７】第１実施形態のフュエルリカバー時ゲインＫＧＺ１の演算を説明するためのフローチャートである。
【図１８】第１実施形態のフュエルリカバー時ゲインＫＧＺ１、ＫＧＺ２の特性図である。
【図１９】第１実施形態のフュエルリカバー時の波形図である。
【図２０】第１実施形態のロックアップ領域の判定を説明するためのフローチャートである。
【図２１】第１実施形態のロックアップ領域を示す特性図である。
【図２２】第１の発明のクレーム対応図である。
【符号の説明】
１ エンジン
４ 燃料噴射弁
７ エアフローメータ
９ 絞り弁開度センサ
１０ クランク角センサ
２０ コントロールユニット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine air-fuel ratio control apparatus.
[0002]
[Prior art]
In a vehicle equipped with an automatic transmission, when the accelerator pedal is released during deceleration (for example, when the idle switch is switched from OFF to ON), the rotational speed is equal to or higher than a predetermined value and the vehicle speed is within a predetermined range. Sometimes a so-called fuel cut is made and from this state
(1) When the vehicle speed drops below the specified value without depressing the accelerator pedal
(2) When the accelerator pedal is depressed to re-accelerate (when the idle switch is switched from ON to OFF),
A so-called fuel recovery is carried out (see "New Electronically Controlled Gasoline Injection", pages 123-124, published by Sankaidou Co., Ltd. in August 1993).
[0003]
[Problems to be solved by the invention]
By the way, the deviation from the target value of the air-fuel ratio at the time of acceleration / deceleration of the engine is caused by the quantitative change of the so-called wall flow fuel that adheres to the intake manifold, the intake port, etc., flows in the liquid state and flows into the cylinder. Therefore, there is a so-called wall flow correction using the excess and deficiency due to this wall flow fuel as a correction amount. This wall flow correction is not limited to acceleration / deceleration, but also during fuel cut when the wall flow fuel changes greatly. Also work. For example, there are wall flow fuels that have a relatively low response rate because they are not directly injected into the cylinder, and those that have a relatively high response rate because they are mainly injected directly into the cylinder. As a correction amount relating to slow wall flow fuel, a transient correction amount Kathos is introduced, and as a correction amount relating to fast wall flow fuel, a cylinder specific increase / decrease correction amount Chosn and a cylinder specific asynchronous injection pulse width Injsetn are introduced (Japanese Patent Laid-Open No. Hei 3). No. 111639).
[0004]
In this type of wall flow correction, the wall flow fuel is predicted in accordance with the decrease in the wall flow fuel at the time of fuel cut, and the fuel flow is increased by an amount corresponding to the loss of the wall flow fuel at the time of fuel cut at the time of fuel recovery. Therefore, the air-fuel ratio at the initial stage of fuel recovery can be made close to the stoichiometric air-fuel ratio, so that the engine-generated torque rises stepwise during fuel recovery as shown in the fourth stage of FIG.
[0005]
In this case, since the torque requirements are different between the above (1) and (2), the wall flow correction is performed at the time of fuel recovery in the case of (2) as shown by the solid line in the first stage in FIG. During the fuel recovery in the case of (1), the wall flow correction is not performed as shown by the broken line in the first row of FIG. During fuel recovery in the case of (2), the torque generated by the engine rises stepwise due to wall flow correction and responds to the acceleration request (see the solid line in the third stage in FIG. 16). At the time of fuel recovery in the case of 1 ▼, the torque generated by the engine rises gently (see the broken line in the third stage in FIG. 16), and the torque shock is reduced.
[0006]
Note that the waveform of the fuel injection pulse width Tin when there is a wall flow correction in the first line in FIG. 16 is modeled and actually shown in the lowermost stage of FIG. That is, in addition to the cylinder air amount equivalent pulse width Avtp determined from the operating conditions at the time of fuel recovery, the transient correction amount Katos works relatively long, and further, the cylinder specific increase / decrease correction amount Chosn and the cylinder specific asynchronous injection pulse width Injsetn are only short. (For example, Chosn and Injsetn are added once for each cylinder).
[0007]
However, in the case of (1) above, even if the vehicle speed decreases without depressing the accelerator pedal, the decrease in vehicle speed (engine speed) is not uniform. For example, there is a sudden deceleration in addition to a slow deceleration. If the torque is gradually raised even during the fuel recovery from, recovery from a sudden drop in rotation during sudden deceleration is delayed, leading to an engine stall.
[0008]
In particular, when the automatic transmission is equipped with a so-called lockup mechanism that directly connects the engine and the automatic transmission, the accelerator pedal is depressed when the engine and the automatic transmission are directly connected (lockup region). If the fuel recovery is performed after the vehicle speed drops and the fuel cut occurs, the increase in the engine speed is delayed by the amount of the automatic transmission load, so a lockup release signal is output before the fuel recovery is performed. However, the fuel after the vehicle cuts down without the accelerator pedal being depressed due to a response delay from when the lockup release signal is given until the lockup mechanism is actually released. The engine and the automatic transmission may be directly connected at the recovery start timing. That is, the engine and the automatic transmission are directly connected to each other when the fuel is recovered from sudden deceleration of the fuel recovery after the vehicle speed is reduced and the vehicle is cut without stepping on the accelerator pedal, and the lockup mechanism is delayed. When in a state, it is conceivable that a sudden drop in rotation does not stop, leading to an engine stall.
Therefore, the present invention providesEven if the engine and automatic transmission are directly connected at the start of fuel recovery from sudden deceleration, engine stall due to sudden drop in rotation is prevented.For the purpose.
[0009]
[Means for Solving the Problems]
As shown in FIG. 22, the first invention is a means 31 for calculating the basic injection amount Tp based on the engine load and the rotational speed, and a means 32 for calculating an increase correction amount related to wall flow fuel at the time of fuel recovery. An air-fuel ratio control of the engine comprising means 33 for calculating a value obtained by correcting the basic injection amount Tp with this increase correction amount as a fuel injection amount at the time of fuel recovery, and means 34 for supplying fuel of this injection amount to the engine In the device, means 35 for determining whether or not the vehicle speed has been reduced and the fuel cut has been reached without depressing the accelerator pedal, and from this determination result, when the vehicle speed has been reduced and the fuel cut has been made without depressing the accelerator pedal, the fuel At the time of fuel recovery after cutting, a predetermined period immediately before the fuel recovery (for example, a predetermined time or a predetermined clan) Provided a means 36 for correcting the angular section) side the increase correction amount as the rotational speed decrease amount ΔN increases per increasesAnd the increase correction amount is further increased when the rotational speed reduction amount ΔN per predetermined period is large and the automatic transmission is in the lockup region..
[0011]
First2In the first aspect of the present invention, in the first aspect of the invention, the increase correction amount related to the wall flow fuel is the first correction amount Chosn related to the wall flow fuel having a quick response and is an injection amount supplied in synchronization with engine rotation. This is a correction amount to be added to the amount Tp.
[0012]
According to a fourth aspect, in the third aspect, the rotational speed reduction amount ΔN per predetermined period is large and the automatic transmission is in a lockup region.1The correction amount Chosn is corrected to the increase side.
[0013]
First3In the invention of the2In this invention, temperature correction is performed on the first correction amount Chosn.
[0014]
First4In the first aspect of the invention, the increase correction amount related to the wall flow fuel in the first invention is the second correction amount Injsetn related to the fast response wall flow fuel, and is an asynchronous injection amount that is injected asynchronously with the engine rotation during rapid acceleration. is there.
[0015]
First5In the invention of the4In this invention, there is provided means for calculating the basic injection amount for each cylinder as a synchronous injection amount to be supplied in synchronization with the engine rotation, and in order to rescue the first intake after the determination at the time of sudden acceleration, excessive injection is performed by the asynchronous injection. A value obtained by subtracting the predicted value ERACIn from the synchronous injection amount only at the synchronous injection timing that comes immediately after the asynchronous injection, and the amount by which the wall flow is reduced by the port flow velocity in the first intake. Is again calculated for each cylinder as a synchronous injection amount.
[0016]
In the eighth invention, in the sixth or seventh invention, the asynchronous injection amount Injsetn is corrected to the increase side when the rotational speed reduction amount ΔN per predetermined period is large and the automatic transmission is in the lockup region.
[0017]
First6In the invention of the4 or 5In the invention, temperature correction is performed on the asynchronous injection amount Injsetn.
[0018]
【The invention's effect】
In the first aspect of the invention, even when the vehicle speed decreases without depressing the accelerator pedal and the fuel cut occurs, the amount of decrease in engine speed ΔN per predetermined period immediately before the fuel recovery covers increases during the fuel recovery from the sudden deceleration. Since the increase correction amount becomes large (the engine-generated torque rises rapidly), it is possible to prevent a sudden decrease in rotation at the time of fuel recovery from sudden deceleration. In addition, when the vehicle speed is reduced without depressing the accelerator pedal and the fuel cut occurs, the amount of increase correction is set at the time of fuel recovery from slow deceleration where the decrease amount ΔN of the engine speed per predetermined period immediately before fuel recovery becomes small. Since it becomes smaller (the engine generated torque rises gently), it is possible to prevent torque shock during fuel recovery from slow deceleration.
[0019]
Thus, according to the first aspect of the present invention, when the vehicle speed is reduced without depressing the accelerator pedal and the fuel is cut, the fuel is recovered according to the amount of decrease in the rotational speed per predetermined period immediately after the fuel cut. Because the engine generated torque is controlled, the recovery shock during slow deceleration and the engine stall during sudden deceleration can be reduced even in the case of fuel recovery after the vehicle speed has been reduced and the fuel has been cut without depressing the accelerator pedal. Can be compatible.
[0020]
When the automatic transmission is equipped with a so-called lockup mechanism in which the engine and the automatic transmission are directly connected, the vehicle speed without stepping on the accelerator pedal when the engine and the automatic transmission are directly connected (lockup region) When the fuel recovery is performed after the fuel cut occurs and the fuel is cut, the increase in the engine speed is delayed by the load of the automatic transmission, so the lockup release signal is output before the fuel recovery is performed. However, due to a delay in response from when the lock-up release signal is given to when the lock-up mechanism is actually released, the vehicle speed drops without depressing the accelerator pedal, and the fuel cover after the fuel cut occurs. The engine and the automatic transmission may be directly connected at the start timing. That is, the engine and the automatic transmission are directly connected to each other when the fuel is recovered from sudden deceleration of the fuel recovery after the vehicle speed is reduced and the vehicle is cut without stepping on the accelerator pedal, and the lockup mechanism is delayed. When in a state, it is conceivable that a sudden drop in rotation does not stop, leading to an engine stall.
[0021]
At this time (that is, in the case of the fuel recovery after the vehicle speed is reduced and the fuel is cut without depressing the accelerator pedal, and when the rotational speed reduction amount ΔN per predetermined period immediately before the fuel recovery is large and in the lock-up region) The second1In the present invention, the increase correction amount is further increased.. OneIn other words, the engine and the automatic transmission stay in the direct connection state at the start timing of the fuel recovery from the sudden deceleration of the fuel recovery after the vehicle speed drops and the fuel cut occurs without depressing the accelerator pedal. In response to the increase in the load of the automatic transmission relative to the engine,1In the invention of theRisoAs a result, the vehicle speed can be increased without depressing the accelerator pedal due to a delay in response from when the lockup release signal is given until the lockup mechanism is actually released. Even if the engine and the automatic transmission are in the direct connection state at the fuel recovery cover start timing from the sudden deceleration of the fuel recovery after the fuel cut at the time of the fuel cut, it is Can be prevented.
[0022]
First2And second4In each of the inventions, the load equivalent amount from the previous injection is decreased at a predetermined rate for each injection timing in accordance with the disappearance of the wall flow fuel at the time of fuel cut, and if it is in the slow acceleration state at the time of subsequent fuel recovery,2In the present invention, the first correction amount Chosn is used to perform synchronous injection, and if it is in the state of rapid acceleration during the subsequent fuel recovery, the first correction amount Chosn is used.4Asynchronous injection is performed using the asynchronous injection amount Injsetn in this invention, so that the engine-generated torque rises step by step at each fuel recovery, but after the vehicle speed decreases without depressing the accelerator pedal and fuel cut occurs Even in the case of the fuel recovery cover, if the engine generated torque rises stepwise, a torque shock will occur due to a sudden increase in torque, so the fuel recovery after the vehicle cuts down and fuel cut occurs without stepping on the accelerator pedal. The current situation is that the torque is gradually raised by not performing the wall flow correction only in the case of.
[0023]
However, even in the case of fuel recovery after the vehicle speed has been reduced and the fuel has been cut without depressing the accelerator pedal, if the torque is gradually raised during fuel recovery from sudden deceleration, It is considered that recovery from a sudden drop in rotation is delayed, leading to an engine stall.
[0024]
On the other hand, in the case of fuel recovery after the vehicle speed has been reduced and the fuel has been cut without depressing the accelerator pedal,2According to the invention, the wall flow correction is performed by correcting the basic injection amount Tp with the first correction amount Chosn, and the fuel recovery after the fuel cut is performed when the vehicle speed is reduced without depressing the accelerator pedal and the fuel cut is reached. Sometimes, the first correction amount Chosn is greatly decreased as the rotational speed reduction amount per predetermined period immediately before the fuel cover decreases,4In this invention, the wall flow correction is performed by immediately supplying the engine with the asynchronous injection amount Injsetn for each cylinder at the time of sudden acceleration, and when the fuel speed is reduced without the accelerator pedal being depressed, At the time of fuel recovery, the asynchronous injection amount Injsetn is corrected so as to decrease as the rotational speed reduction amount per predetermined period immediately before the fuel recovery decreases, so the vehicle speed decreases without depressing the accelerator pedal and fuel cut occurs. After the fuel recovery from the slow deceleration, the first correction amount becomes smaller and the torque increase during the fuel recovery from the slow deceleration becomes gradual. On the other hand, the fuel recovery from the sudden deceleration Sometimes during fuel recovery from slow deceleration Correction amount Rimodai 1 is increased, the torque increase during fuel recovery from the rapid deceleration becomes abruptly.
[0025]
In this way2The second4In each of the inventions, the wall flow correction is performed also in the case of the fuel recovery after the vehicle speed is lowered and the fuel cut is made without depressing the accelerator pedal, and the rotation speed reduction amount ΔN per predetermined period at the start of the fuel recovery. By controlling the engine generated torque according to the situation, it is possible to avoid a sudden drop in rotation from sudden deceleration in the case of fuel recovery after the vehicle speed has been reduced and the fuel has been cut without depressing the accelerator pedal. Torque shock at the time of fuel recovery from slow deceleration can be avoided.
[0026]
First3In the present invention, even if the temperature is different, the first wall flow correction amount Chosn is changed to the first wall flow correction amount Chosn.6In this invention, the asynchronous injection amount Injsetn can be provided with high accuracy even if the temperatures are different.
[0027]
First5In this invention, it is possible to give a substantially stoichiometric air-fuel mixture even at the synchronous injection timing that comes immediately after asynchronous injection.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, reference numeral 1 denotes an engine body, and intake air is supplied from an air cleaner through an intake pipe 3 to a cylinder. The fuel is injected from the fuel injector 4 toward the intake port of the engine 1 based on an injection signal from the control unit 20 so as to have a predetermined air-fuel ratio according to operating conditions.
[0029]
The control unit 20 includes a Ref signal (reference position signal) and a Pos signal (1 ° signal) from the crank angle sensor 10, an intake air amount signal from the air flow meter 7, and an O installed upstream of the three-way catalyst 6.₂An air-fuel ratio (oxygen concentration) signal from the sensor 12, an engine cooling water temperature signal from the water temperature sensor 11, a throttle valve 8 opening signal from the throttle sensor 9, and the like are input. The basic injection pulse width Tp is calculated from Qa and the engine speed N, and wall flow correction is performed during acceleration / deceleration. The deviation from the target value of the air / fuel ratio during acceleration / deceleration of the engine is caused by the quantitative change of so-called wall flow fuel that adheres to the intake manifold or intake port and flows into the cylinder through the wall surface in the liquid state. The fuel correction is performed by using the excess / deficiency due to the wall flow fuel as a correction amount. The wall flow correction works not only at the time of acceleration / deceleration but also at the start and fuel cut when the wall flow fuel changes greatly.
[0030]
Here, there are two types of wall-flow fuel, one that has a small amount of direct flow into the cylinder and a relatively slow response, and one that has a direct flow into the cylinder that has a relatively fast response. As a correction amount relating to slow wall flow fuel, a transient correction amount Kathos described later is introduced, and as a correction amount relating to fast wall flow fuel, a cylinder specific increase / decrease correction amount Chosn and cylinder specific asynchronous injection pulse width Injsetn are introduced. . With these values, for example, as shown in the lowermost stage of FIG. 13, Katos works for a relatively long time immediately after fuel recovery, and Chosn and Injsetn work for a short time.
[0031]
The contents of this control executed by the control unit will be described according to the following flowchart.
[0032]
The wall flow correction described below is detailed in Japanese Patent Laid-Open No. 3-11639. Here, only the part related to the present invention will be outlined with reference to this publication, and each control at the time of fuel cut and fuel recovery will be supplemented.
[0033]
The flowchart of FIG. 2 is for calculating the cylinder specific synchronous injection pulse width Tin [ms], as well as calculating the cylinder specific asynchronous injection pulse width Injsetn [ms] and executing asynchronous injection at regular intervals ( For example, every 10 ms).
[0034]
In the flow of FIG. 2 (also in FIGS. 8 and 12 described later), when the value is for each cylinder, the cylinder number n is added to the end of the symbol to distinguish (for example, ΔAvtpn, FIG. 2). Chosn, Tin, Injsetn, ERACIn, ERACIn (old), CNTn, Avtpoint, Avtpoint (old), Avtpoint, Avtpoint (old) in FIG. 8, CNTn, ERACIn, CNTn in FIG.
[0035]
Further, the value of a symbol relating to a numerical value (for example, CNTn in FIGS. 2, 8, and 12) is initialized to 0 at the start unless otherwise specified, and flags (for example, FFC, FRC, FIG. Symbols representing FRC in FIGS. 12, 14, and 17 and FLU in FIG. 20 are reset to “0” at the start unless otherwise specified.
[0036]
In step 1, the basic injection pulse width Tp [ms] is determined from the intake air flow rate Qs [g / s] obtained from the air flow meter output and the engine speed N [rpm] obtained from the crank angle sensor.
Tp = (Qs / N) × K × Ktrm (1)
Where K is a constant
Ktrm: Trimming factor
Calculate with the following formula.
[0037]
Here, K in equation (1) is a constant determined so that a stoichiometric air-fuel mixture can be obtained, and Ktrm is a specific constant determined by the flow rate characteristics of the injector 4.
[0038]
In Step 2, the product N × V of the rotational speed N and the cylinder volume V [cc] and the total flow passage area Aa [cm] of the throttle valve portion.²] To obtain a weighted average coefficient Fload [%] with reference to a predetermined map. The total flow area Aa is the flow area of the throttle valve [cm²] And the flow area of the idle control valve and air regulator [cm²] Is added.
[0039]
In step 3, the cylinder air amount equivalent pulse width Avtp [ms] is set.
Avtp = Tp × Fload + Avtp (old) × (1−Fload) (2)
However, Avtp (old): the previous value of Avtp
Calculate with the following formula. Here, Avtp is a load equivalent amount. Note that the value of Avtp (old) is initialized to 0 at start-up together with ERACIn (old), Avtppoint (old), and N (old) described later.
[0040]
In step 4, it is judged from the flag FFC whether or not the fuel cut is being performed. When the flag FFC = 1, it is determined that the fuel cut is being performed, and the process proceeds to step 15. When FFC = 0, it is determined that the fuel cut is not being performed, and the process proceeds to step 5 and subsequent steps.
[0041]
In step 5, the difference ΔAvtpn (= Avtp−Avtpoint) between Avtp and Avtppoint (Avtp at the time of previous injection (for each cylinder)) is compared with the interrupt injection determination level LASNI. If ΔAvtpn ≦ LASNI, it is not during rapid acceleration (that is, In step 6, it is determined that the vehicle is slowly accelerating or slowly decelerating.
Chosn = ΔAvtpn × Gztwp; slow acceleration (3)
However, Gztwp: increase gain [unknown number]
Or by the formula
Chosn = ΔAvtpn × Gztwm; During slow deceleration (4)
Gztwm: Weight loss gain [Anonymous number]
The cylinder-specific increase / decrease correction amount Chosn [ms] is calculated by Step 6 is represented by equation (3).
[0042]
Here, Chosn is a correction amount related to the wall flow fuel having a quick response.
[0043]
Gztwp in the above expression (3) and Gztwm in the expression (4) are for performing water temperature correction as described later.
[0044]
It should be noted that if the determination level LNSNI is set to a small value, injection can be performed with good response to minute changes in the intake air flow rate and minute changes in the fuel wall flow (more small pulses are injected, and Chosn is reduced). . However, it is desirable to make Injsetn, which will be described later, small enough not to enter the accuracy deterioration zone of the injector.
[0045]
Note that KGZ1 in step 6 (also in step 9 described later) is newly introduced in the present invention and will be described in detail later.
[0046]
In step 7, it is checked whether or not the calculation of the cylinder-specific increase / decrease correction amount Chosn for one cycle (6 cylinders for a six-cylinder engine) has been completed, and if the calculation of Chosn has been completed for all the cylinders, the process proceeds to step 8.
[0047]
This is because Chosn (Injsetn and ERACIn during rapid acceleration) needs to be calculated for each cylinder because the load equivalent amount ΔAvtpn from the previous injection differs for each cylinder. For example, when the ignition sequence is 1-5-3-6-2-4, if Chosn is calculated for the first cylinder, Chosn has not been calculated for the remaining five cylinders. Chosn is calculated for the numbered cylinder. Subsequently, Chosn is calculated in the order of the third cylinder, the sixth cylinder, the second cylinder, and the fourth cylinder. This completes Chosn calculation for all cylinders, and proceeds from step 7 to step 8. It should be noted that the time required to calculate Chosn for all cylinders is sufficiently shorter than 10 ms, which is the Tin calculation interval, and a situation occurs in which the next Tin calculation timing comes before the calculation for all cylinders is completed. There is nothing.
[0048]
In step 8, the cylinder-specific synchronous injection pulse width Tin [ms] is set.
Tin = {(Avtp + Kathos) × Tfbya × α + (Chosn−ERACIn)} × 2 + Ts (5)
However, Kathos: transient correction amount [ms]
Tfbya: target fuel / air ratio equivalent [unnamed number]
α: Air-fuel ratio feedback correction coefficient [Anonymous number]
ERACIn: Over-cylinder correction amount by cylinder [ms]
Ts: Invalid pulse width [ms]
The flow of FIG. 2 is completed.
[0049]
Here, Kathos is a correction amount for the slow-response wall flow fuel. Tfbya is the sum of the water temperature increase correction coefficient Ktw, the post-startup increase correction coefficient Kas, and the like. Immediately after an unstable engine cold start, Tfbya becomes a value greater than 1.0 and fuel increase is performed. Even if an injection signal is output to the injector, the injector opens with a response delay, so the value considering the response delay is Ts. ERACIn will be described later. 2 in front of Ts on the right side of the equation (5) is a value that is necessary for sequential injection (injection once per engine rotation per cylinder).
[0050]
On the other hand, when ΔAvtpn> LSNSNI (at the time of rapid acceleration) in step 5, the process proceeds to step 9 to set the cylinder specific asynchronous injection pulse width Injsetn [ms].
Injsetn = ΔAvtpn × Gztw × Gzcyl + Ts (6)
However, Gztw: Asynchronous injection gain [unnamed number]
Gzcyl: correction gain by asynchronous injection timing (during cycle) [unknown number]
In step 10, the over-cylinder over-jet correction amount ERACIn is
ERACIn = ERACIn (old) + ΔAvtpn × Gztw × (Gzcyl-ERACP) (7)
However, ERACIn (old): previous value of ERACIn
Injsetn in the equation (6) is immediately output to the I / O port 24 in step 11 to perform asynchronous injection.
[0051]
In the equation (7), the first term on the right side means the amount of excessive ejection up to the previous time, and the second term means the current amount of excessive ejection. ERACIn predicts the amount of over-injection to save the first intake after the determination of sudden acceleration by asynchronous injection and the amount of wall flow decreased by the port flow velocity at the first intake. The synchronous injection is reduced by this ERACIn only at the synchronous injection timing immediately after the injection.
[0052]
Next, the physical meanings of Gztw and Gzcyl in the equations (6) and (7) are as follows.
[0053]
The fuel injected from the injector is not all sucked into the cylinder in the first intake stroke immediately after the injection, but is once attached to the intake pipe wall, and only a predetermined proportion of the fuel evaporated from the intake pipe is sucked. The When the fuel injection amount is changed in steps and the injection is terminated, the ratio of the fuel sucked in the first intake stroke immediately after the injection of the injected fuel is set as the direct rate Z, and the characteristic of Z is shown in FIG. Z varies greatly depending on the injection end timing and the coolant temperature. In order to consider Z that changes depending on this injection end timing and cooling water temperature, the gain corresponding to the inverse of Z is divided into a water temperature term and an injection timing term.
Water temperature term: Gztw = f (Tw)
Injection timing term: Gzcyl = f (1 / T)
T: Crank angle between injection timing and intake stroke
Represented as:
[0054]
Here, Gztw gives a gain at a position where the injection timing is farthest from the intake stroke (leftmost position in FIG. 3) at each water temperature (see FIG. 5), and Gztw is corrected by Gzcyl. Gzcyl = 1 is set at a position farthest from the intake stroke, and a larger value is given to Gzcyl as the injection timing approaches the intake stroke.
[0055]
In this way, by giving the gains of Gzcyl and Gztw, the closer the injection timing is to the intake stroke (the shorter the waiting time until the intake stroke) and the lower the cooling water temperature, the higher the Injsetn in the equation (6). Increases, and the second term in the equation (7) (the amount of excessive spraying this time) also increases.
[0056]
Note that during sudden acceleration when the change in suction negative pressure during the intake stroke becomes large, the flow velocity associated with the pressure change in the cylinder (almost close to the intake pipe pressure change) is added to the flow velocity associated with the piston operation. When the pressure change overlaps with the intake stroke, the port portion flow velocity becomes higher than in the case other than the intake stroke, thereby promoting the evaporation of the fuel adhering to the intake pipe wall and increasing Z. During the intake stroke, extra fuel corresponding to the change in the air amount is required, and this change in the air amount is also added to Gzcyl.
[0057]
(7) ERACP is the amount of fuel required to save the first cycle immediately after asynchronous injection from leaning,
ΔAvtpn × Gztw × ERACP
As described above, since the injection timing term Gzcyl during the intake stroke is the sum of the air amount change and the wall flow increase, the ERACP value at this time is the air amount change. The reference value ERACP # when the minute and the wall flow increase are combined is used. Since Gzcyl other than the intake stroke is only the increase in the wall flow, the reference value ERACPH # for the increase in the wall flow is used as the value of ERACP at this time.
[0058]
In step 12, it is judged from the flag FRC whether or not the fuel recovery is in progress. Only when the flag FRC = 1 (when fuel is recovered), the routine proceeds to step 13, and after entering 1 into the counter CNTn of the cylinder subjected to asynchronous injection, the routine proceeds to step 14 and when the flag FRC = 0 (not when fuel is recovered) Proceeds directly to step 14. The counter CNTn is necessary to determine the end of the fuel recovery condition, and the end determination of the fuel recovery condition will be described later.
[0059]
In step 14, the value of Avtppoint of the cylinder that has performed asynchronous injection is transferred to the memory Avpoint (old) of the same cylinder, and then the Avtp at that time is stored in the Avtppoint of the cylinder that has performed asynchronous injection. In other words, the engine load equivalent amount at the time of asynchronous injection is stored for each cylinder in Avpoint. Further, since Chosn is not required at the time of asynchronous injection, “0” is set in Chosn in step 14 (reset).
[0060]
In step 7, it is checked whether the calculation of Injsetn and ERACIn and the interrupt injection have been completed for all six cylinders. At the time of rapid acceleration, the processes of steps 9, 10, 11, 12, 13, and 14 are performed for all the cylinders.
[0061]
If the ignition sequence is 1-5-3-6-2-4 again, the calculation of Injsetn and ERACIn for the first cylinder and interrupt injection will be performed first. Since calculation of ERACIn and interruption injection are not yet performed, calculation of Injsetn and ERACIn and interruption injection are performed for the fifth cylinder. Subsequently, calculation of Injsetn and ERACIn and interruption injection are performed in the order of the third cylinder, the sixth cylinder, the second cylinder, and the fourth cylinder. This completes the calculation of Injsetn and ERACIn and interrupt injection for all cylinders, and proceeds from step 7 to step 8. The time required for the calculation of all cylinders of Injsetn and ERACIn and the execution of asynchronous injection for all the cylinders is sufficiently shorter than the calculation interval of 10 ms, which is the time for the next Tin before the calculation for all cylinders is completed. There will never be a situation in which the calculation timing comes.
[0062]
The flowchart of FIG. 4 is for calculating the above-described asynchronous injection gain Gztw, increase gain Gztwp, and decrease gain Gztwm, and is executed every 1 sec.
[0063]
In steps 21, 22 and 23, referring to the tables of FIGS. 5, 6 and 7 from the cooling water temperature Tw, the asynchronous injection gain Gztw [anonymous number], the increase gain Gztwp [anonymous number], and the decrease gain Gztwm [anonymous number]. ] For each. Since the wall flow fuel increases as the cooling water temperature decreases, Chosn, Injsetn, and ERACIn are increased as the cooling water temperature Tw decreases. The two gains Gztwp and Gztwm thus calculated are used in Step 6 of FIG. 2 to select Chosn, and the asynchronous injection gain Gztw is used in Steps 9 and 10 of FIG. 2 to determine Injsetn and ERACIn.
[0064]
The flowchart in FIG. 8 is for execution at the injection timing. In sequential injection, every time a Ref signal is input to each cylinder, in a six-cylinder engine, six Ref signals rise with two engine revolutions. That is, the injection timing for each cylinder comes every 120 ° in crank angle.
[0065]
In step 31, cylinder discrimination is performed, and Tin (already obtained in step 8 of FIG. 2) is output to the I / O port 24 in step 32 to perform synchronous injection.
[0066]
In step 33, it is determined whether or not it is during fuel cut. If not during fuel cut, the value of Aptpoint of the cylinder that has performed synchronous injection at that timing in step 34 is transferred to the memory Aptpoint (old) of the same cylinder. Avtp at that timing is stored in Avtppoint of the cylinder that has performed synchronous injection. In other words, the engine load equivalent amount at the time of synchronous injection is stored for each cylinder in Avpoint. As described in step 14 of FIG. 2, since the engine load equivalent amount at the time of asynchronous injection is also stored in Avtpoint, as a result, Avtpoint is at the time of injection (regardless of synchronous or asynchronous). It represents the load equivalent amount.
[0067]
On the other hand, when the fuel cut occurs, the process proceeds to step 35.
Avtpoint = Aptpoint (old) × FCTP0 # (8)
However, Avtpoint (old): The previous value of Avtpoint
FCTP0 #: Decrease rate [nameless number]
After updating Aptpoint according to the following equation, the value of this Aptpoint is transferred to the memory Aptpoint (old) of the cylinder that has performed synchronous injection for the next control.
[0068]
Since the wall flow fuel disappears every cycle at the time of fuel cut, the reduction rate FCTP0 # is set in accordance with the decrease in the wall flow fuel, and the Avtpoint is decreased (see FIG. 13).
[0069]
Steps 36 and 37 are the same as steps 12 and 13 in FIG. When the flag FRC = 1 (when fuel is recovered), the routine proceeds to step 37, where 1 is entered in the counter CNTn of the cylinder that has performed synchronous injection at the injection timing, and then to step 38, and when the flag FRC = 0 (fuel) If it is not during recovery), the process proceeds directly to step 38.
[0070]
In step 38, it is determined whether it is the first time after the asynchronous injection, and if it is not the first time after the asynchronous injection, the routine proceeds to step 39 and "0" is set in ERACIn (reset). That is, in each cylinder, ERACIn is added to the synchronous injection amount only at the first synchronous injection timing immediately after asynchronous injection (the amount of excessive injection due to asynchronous injection is reduced).
[0071]
Here, focusing on one of the six cylinders (specific cylinder), FIG. 9 and FIG. 10 show how the high frequency component (abbreviated as S in the figure) of the wall flow fuel changes. In FIG. 9, only the synchronous injection is performed in the specific cylinder for slow acceleration, and in FIG. 10, three asynchronous injections are performed in the specific cylinder for rapid acceleration.
[0072]
With reference to FIG. 10 in particular, what will happen specifically to the above-mentioned ERACIn that is the over-jet correction amount will be described next. In addition, the time from t1 to t10 is marked on the 10 ms mark, the synchronous injection just before the asynchronous injection is a, the asynchronous injection is a, c, and d, and the first synchronous injection just after that is marked with an o. The above equation (5) is for simplicity
Tin = Ten × 2-Ts
However, Ten: Effective pulse width by cylinder
Furthermore, Kathos is omitted, Tfbya and α are both set to 1.0,
Ten = (Avtp + Chosn−ERACIn) (i)
Think of the following formula.
[0073]
(1) Time point t1: Chosn (> 0) and Ten are calculated. At this time, ERACIn = 0.
[0074]
(2) Time point t2: Injsetn is calculated and immediately injected. This is the first asynchronous injection (see a). At this time, ERACIn is calculated. ERACIn = ΔAvtpn × Gztw × (Gzcyl−ERACP) from ERACIn (old) = 0. ERACIn at this time is set to E1 (> 0).
[0075]
(3) Time point t3: Chosn (> 0) and Ten are calculated. At this time, ERACIn = E1 is maintained.
[0076]
(4) Time point t4: Injsetn is calculated and immediately injected. This is the second asynchronous injection (see C). At this time, ERACIn = E1 + ΔAvtpn × Gztw × (Gzcyl−ERACP). Therefore, if the second term on the right side is E2 (> 0), ERACIn = E1 + E2.
[0077]
(5) Time point t5: Chosn (> 0) and Ten are calculated. At this time, ERACIn = E1 + E2, which is the same as the time t4.
[0078]
(6) Time point t6: Injsetn is calculated and immediately injected. This is the third asynchronous injection (see D). At this time, ERACIn = (E1 + E2) + ΔAvtpn × Gztw × (Gzcyl−ERACP). Therefore, if the third term on the right side is E3 (> 0), ERACIn = E1 + E2 + E3.
[0079]
(7) Time point t7: Chosn (= 0) and Ten are calculated. For ERACIn, ERACIn = E1 + E2 + E3, which is the same as the time t6.
[0080]
(8) Time point t8: Chosn (= 0) and Ten are calculated. For ERACIn, ERACIn = E1 + E2 + E3, which is the same as the time t6.
[0081]
Note that the time point t8 is immediately before the synchronous injection timing (time point t9).

The effective pulse width Ten given by the following equation is used for the synchronous injection at the next time t9.
[0082]
{Circle around (9)} Time t9: t9 is the timing of synchronous injection. At this time, synchronous injection is performed with Ten of the above equation (ii) calculated at the timing of t8 (see (e)). In the equation (ii), E1 is an excessive injection amount in the first asynchronous injection, E2 is an excessive injection amount in the second asynchronous injection, E3 is an excessive injection amount in the third asynchronous injection, and these excessive injection amounts ( That is, E1 + E2 + E3) is reduced from the synchronous injection amount (Avtp) at the synchronous injection timing that comes immediately after the end of asynchronous injection. After the synchronous injection amount is corrected to decrease in this way, ERACIn = 0 is set in preparation for the next asynchronous injection.
[0083]
At time 10t10: Chosn (= 0) and Ten are calculated. For ERACIn, ERACIn = 0.
[0084]
In this way, when asynchronous injection and the first synchronous injection immediately thereafter are performed, the air-fuel ratio can be controlled to the stoichiometric air-fuel ratio for each cylinder before and after the rapid acceleration.
[0085]
Next, the flowchart of FIG. 11 is for determining the fuel recovery condition, and the flowchart of FIG. 12 is for determining the end of the fuel recovery condition, and is constant independently of FIGS. Run every hour. Note that the flow of FIG. 12 is executed following the flow of FIG.
[0086]
First, referring to FIG. 11, in step 41, it is determined whether or not the fuel is cut. The process proceeds to step 42 and later only when the fuel is cut.
[0087]
In steps 42, 43 and 44, the following conditions are satisfied:
<1> When the vehicle speed VSP is a predetermined value (for example, 8 km / h) or less,
<2> When the idle switch is turned off
<3> When the rotational speed N of the vehicle with an automatic transmission becomes a predetermined value or less (for example, a predetermined value or less according to the coolant temperature or 2000 rpm or less)
Is checked one by one, and if any of the conditions is not satisfied, the process proceeds to step 45 and “0” is set in the flag FRC, and if any of the conditions is satisfied (when the fuel recovery condition is satisfied) In steps 46 and 47, the flag FRC is set to “1” and the flag FFC is reset to “0”.
[0088]
Turning to FIG. 12, in step 51, it is determined by the flag FRC whether fuel recovery is being performed. When FRC = 1 (during fuel recovery), the counter CNTn is checked in step 52, and the counter CNTn becomes 1 in all cylinders. If YES, the routine proceeds to step 53, where the flag FRC is reset to "0", and the counter CNTn is reset to 0 for all cylinders at step 54 for the next fuel recovery control. That is, the fuel recovery is finished at the timing when one injection (synchronous injection or interrupt injection) is finished in each cylinder from the start of the fuel recovery.
[0089]
A brief description of how the injection is performed at the time of fuel recovery is given for the above specific cylinder. As shown in FIG. 13, when ΔAvtpn at the start timing of fuel recovery exceeds LASNI, Injsetn, ERACIn is calculated, asynchronous injection is performed after the start of fuel recovery, and the amount of ERACIn is reduced from the synchronous injection amount only at the first synchronous injection timing immediately after the end of asynchronous injection. Asynchronous injection at the time of fuel recovery starts from a cylinder that has synchronous injection timing during fuel cut and that has received a fuel recovery signal during the intake stroke. On the other hand, when ΔAvtpn at the start timing of fuel recovery is equal to or lower than LASNI, Chosn is calculated using the ΔAvtpn, and the synchronous injection amount with Chosn added is supplied for each cylinder at the synchronous injection timing after the start of fuel recovery. .
[0090]
This is the end of the outline of Japanese Patent Application Laid-Open No. 3-11639 and the explanation of the control during fuel cut and during fuel recovery.
[0091]
When a vehicle equipped with an automatic transmission falls from the fuel cut state to (1) the accelerator pedal without depressing the accelerator pedal and falls below a predetermined value, or (2) when the accelerator pedal is depressed to re-accelerate. The so-called fuel recovery is performed, but in the case where the wall flow correction is performed as described above, the wall flow fuel is predicted according to the decrease in the wall flow fuel at the time of the fuel cut, and at the time of the fuel cut at the time of the fuel recovery. Since the air fuel ratio at the initial stage of fuel recovery can be made closer to the stoichiometric air fuel ratio, the engine is generated during fuel recovery as shown in the fourth stage of FIG. Torque rises stepwise.
[0092]
In this case, since the torque requirements are different between the above (1) and (2), the wall flow correction is performed at the time of fuel recovery in the case of (2) as shown by the solid line in the first stage in FIG. During the fuel recovery in the case of (1), the wall flow correction is not performed as shown by the broken line in the first row of FIG. During fuel recovery in the case of (2), the torque generated by the engine rises stepwise due to wall flow correction (see the solid line in the third stage in FIG. 16), which corresponds to the acceleration request, At the time of fuel recovery in the case of 1 ▼, the torque generated by the engine rises gently (see the broken line in the third stage in FIG. 16), and the torque shock is reduced. Note that the waveform of the fuel injection pulse width Tin when there is wall flow correction (the solid line in the first stage in FIG. 16) is modeled and actually shown in the lowermost stage of FIG.
[0093]
However, even in the case of (1), even if the vehicle speed decreases without depressing the accelerator pedal, the decrease in the vehicle speed (engine speed) is not uniform. Even when the fuel is recovered, if the torque is gradually started up in the same manner as in the case of the fuel recovery in the case of (1) above, recovery from a sudden decrease in rotation during sudden deceleration may be delayed, leading to an engine stall. .
[0094]
To deal with thisReference exampleIn contrast to the current situation, wall flow correction is also performed during fuel recovery in the case of <1> (in the case of fuel recovery when the idle switch is ON), and the engine speed per predetermined time at the start of the fuel recovery is The engine generation torque at the time of fuel recovery is newly controlled according to the decrease amount.
[0095]
Specifically, as shown in steps 6 and 9 of FIG. 2, a fuel recovery gain KGZ1 is newly introduced, and instead of the above equations (3), (4), and (6),

The cylinder specific increase / decrease correction amount Chosn and the cylinder specific asynchronous injection pulse width Injsetn are calculated by the following formula.
[0096]
However, KGZ1 is not introduced into the expression for the cylinder-specific over-injection correction amount ERACIn (that is, as it is conventionally).
[0097]
The calculation of KGZ1 in equations (11), (12), and (13) will be described with reference to the flowchart of FIG. The flowchart of FIG. 14 is executed at regular intervals prior to FIG.
[0098]
In steps 61 and 62, it is checked whether or not the current fuel recovery time and whether the idle switch is OFF. If it is during fuel recovery this time and the idle switch is ON, the process proceeds to step 63 to check whether the previous time was during fuel recovery.
[0099]
If the previous time was not during fuel recovery (ie, when switching from fuel cut to fuel recovery), go to step 64;
ΔN = N (old) −N (14)
Where N (old): the previous value of N
The rotational speed reduction amount ΔN [rpm / ms] per predetermined time at the fuel recovery start timing is calculated by the following formula. From this ΔN, the fuel recovery gain KGZ1 [ Anonymous number]. As shown in FIG. 15, KGZ1 is a negative value when ΔN is small (that is, during slow deceleration), and is 0 when ΔN is large (that is, during rapid deceleration).
[0100]
In step 66, the value of N is transferred to the memory ΔN (old) for the next control, and the flow of FIG.
[0101]
On the other hand, since KGZ1 is not necessary when the fuel switch is not at the time of fuel recovery or when the idle switch is OFF even at the time of fuel recovery, the process proceeds to step 67 from steps 61 and 62, and 0 is entered in KGZ1 and the operation in step 66 is The flow in FIG. 14 ends. If the idle switch is ON and the time of fuel recovery continues, steps 64 and 65 are skipped from step 63 and the operation of step 66 is executed.
[0102]
When KGZ1 calculated in this way is used in the above formulas (11), (12), and (13), when the rotational speed reduction amount ΔN per predetermined time at the fuel recovery start timing is small (during slow deceleration) ), Chosn and Injsetn are corrected for reduction, while Chosn and Injsetn are the same as before when ΔN is large (during rapid deceleration).
[0103]
However, in the formula (11), Gztwp + KGZ1 is limited to Gztwp + KGZ1 ≧ 0. The reason for this limitation is as follows. In the original configuration of Chosn, it is determined whether or not Chosn is added as an increase or decrease according to the sign of ΔAvtpn. On the other hand, since Gztwp is a value that only determines the gain, Gztwp ≧ 0. In the present invention, since KGZ1 may be added as a negative value (see FIG. 15), if Gztwm + KGZ1 <0, it is determined whether Chosn is added as an increase or decrease depending on whether ΔAvtpn is positive or negative. become unable. Therefore, by setting Gztwp + KGZ1 ≧ 0, the original configuration of Chosn is maintained. For the same reason, Gztwm + KGZ1 is limited to Gztwm + KGZ1 ≧ 0 in equation (12), and Gztw × Gzcyl + KGZ1 is limited to Gztw × Gzcyl + KGZ1 ≧ 0 in equation (13).
[0104]
here,Reference exampleThe operation of will be described.
[0105]
In addition to the transient correction amount Kathos, the fuel injection control using Chosn and Injsetn in the above formulas (3) and (6) predicts the wall flow fuel according to the decrease in the wall flow fuel at the time of fuel cut. As a result, it is possible to increase the amount of fuel lost by wall flow at the time of fuel cut at the time of fuel recovery, and the air / fuel ratio at the initial time of fuel recovery can be brought close to the stoichiometric air / fuel ratio. Although it starts up stepwise (see the 4th stage in Fig. 16), (1) When the vehicle recovers when the vehicle speed drops below the specified value without depressing the accelerator pedal, and (2) re-accelerates. Since the torque requirement is different from the time of fuel recovery when the accelerator pedal is depressed, By not performed wall flow correction only when fuel recovery merging (see FIG. 16 third stage Looking), the engine torque up gradually, thereby reducing the torque shock. However, in the case of (1) above, even if the vehicle speed decreases without depressing the accelerator pedal, the decrease in vehicle speed (engine speed) is not uniform. For example, there is a sudden deceleration in addition to a slow deceleration. Even when the fuel is recovered from the vehicle, if the torque is gradually started up as in the case of the fuel recovery in the case of (1) above, it is thought that recovery from the sudden decrease in rotation at the time of sudden deceleration is delayed, leading to an engine stall. As mentioned above.
[0106]
On the contraryReference exampleHowever, unlike the current situation, wall flow correction is performed even in the case of fuel recovery when the idle switch is ON, and the gain KGZ1 corresponding to the rotation speed reduction amount ΔN per predetermined time at the start timing of the fuel recovery is newly set. KGZ1 = 0 at the time of fuel recovery from the sudden deceleration (that is, when ΔN is large) in the fuel recovery when the idle switch is ON. At this time, the torque characteristics shown by the solid line in the fifth stage of FIG. 16 are obtained, and a sudden torque increase occurs during fuel recovery from the sudden deceleration, so that a sudden decrease in rotation during sudden deceleration can be avoided.
[0107]
On the other hand, in the case of fuel recovery when the idle switch is ON, by giving a negative value to KGZ1 at the time of fuel recovery from slow deceleration, Chosn in the above equation (11), and in the above equation (13) Each of Injsetn is corrected to decrease. In other words, Chosn and Injsetn both decrease from normal acceleration during fuel recovery from slow deceleration, so the torque increase during fuel recovery is smoothed by that amount (see the broken line in the fifth row in FIG. 16). ).
[0108]
As indicated by the broken line in the fifth stage in FIG. 16, the torque at the time of fuel recovery from slow deceleration (when ΔN is small in the figure) increases stepwise as the combustion proceeds for each cylinder. This corresponds to the generation of torque. In the fifth-stage broken line characteristic in FIG. 16, the combustion for three cylinders coincides with the solid line, but whether the number of cylinders for combustion coincides with the solid line is determined by the fuel recovery gain KGZ1. The number of cylinders is not related to whether the number of cylinders matches the solid line in the combustion.
[0109]
In this wayReference exampleThen, even in the case of fuel recovery when the idle switch is ON, wall flow correction is performed for both slow response and fast response wall flow fuel, and the fuel recovery gain KGZ1 (ie, ΔN) is set. Since the engine generated torque is controlled accordingly, the torque characteristic in the case of fuel recovery when the idle switch is in the ON state is as shown in the fifth stage of FIG. 16, and even in the case of fuel recovery when the idle switch is in the ON state, It is possible to avoid a sudden drop in rotation from sudden deceleration and to avoid a torque shock during fuel recovery from slow deceleration.
[0110]
The flowchart of FIG.Of the present inventionFirst1In an embodiment,Reference exampleThis corresponds to FIG. The same step numbers are assigned to the same parts as those in FIG.
[0111]
When the automatic transmission is equipped with a so-called lockup mechanism that directly connects the engine and the automatic transmission, the idle switch is in the ON state when the engine and the automatic transmission are directly connected (lockup region). When fuel recovery is performed, the increase in engine speed is delayed by the amount of the automatic transmission load, so the lockup release signal is output before performing fuel recovery when the idle switch is ON. Due to a delay in response from when the up release signal is given until the lockup mechanism is actually released, the engine and the automatic transmission may be directly connected at the start timing of the fuel recovery when the idle switch is ON. (See FIG. 19). In other words, in the case of fuel recovery when the idle switch is ON, if the engine and automatic transmission are in the direct connection state during fuel recovery from sudden deceleration and due to the delay in the operation of the lockup mechanism, a sudden drop in rotation will not stop. It can be thought that it leads to the engine stall.
[0112]
So the second1In the embodiment, out of the fuel recovery when the idle switch is in the ON state, the torque generated by the engine is greater in the fuel recovery from the sudden deceleration and in the lockup region than in the fuel recovery from the sudden deceleration and not in the lockup region. Modify Chosn, Injsetn on the side.
[0113]
Specifically, steps 71 and 72 in FIG.Reference exampleIs different. In step 71, it is determined by the flag FLU whether or not it is in the lockup area. When the flag FLU = 1, it is determined that it is in the lock-up region, and in step 72, a fuel recovery gain KGZ2 is obtained from ΔN by referring to a table containing the one-dot chain line in FIG. Put in KGZ1. When the flag FLU = 0 (when not in the lockup area)Reference exampleIn the same manner as described above, the process proceeds from step 71 to step 65, and KGZ1 is obtained from ΔN with reference to a table containing the solid line in FIG.
[0114]
In this embodiment, as shown in FIG. 18, among fuel covers with the idle switch turned ON, during fuel recovery from sudden deceleration (when ΔN is large in the figure), when in the lockup region, KGZ1 ( = KGZ2) is given as a positive value, and Chosn and Injsetn are corrected to increase by this positive amount compared to when not in the lock-up state. Therefore, the torque characteristic at this time is superimposed on the fifth stage in FIG. Shown is a two-dot chain line. In other words, among the fuel covers when the idle switch is ON, the engine and the automatic transmission may actually stay in the direct connection state at the fuel recovery start timing from the sudden deceleration. Corresponding to the increase in the load of the transmission, the torque increase by the load increase is performed by KGZ1, so that the lockup mechanism is actually released after the lockup release signal is given. Even if the engine and the automatic transmission are in the direct connection state at the start timing of the fuel recovery from the sudden deceleration of the fuel recovery with the idle switch ON, It is possible to prevent engine stall caused by rotation dropping.
[0115]
Whether or not the automatic transmission is in the lockup region is actually determined on the side of the automatic transmission control unit (not shown), and the determination result is sent to the engine control control unit via the communication device. 20 is transmitted.
[0116]
For example, the control unit for automatic transmission determines whether or not it is in the lockup region according to the flowchart of FIG. As shown in FIG. 21, the lock-up area is given on a map using the throttle valve opening TVO and the vehicle speed VSP as parameters. If TVO and VSP at that time are in the lock-up area, step 71 to step 72 are performed. Then, an ON signal (lock-up signal) is output to a lock-up solenoid (not shown). If not in the lock-up region, the process proceeds from step 71 to step 74, and an OFF signal (lock-up release signal) is sent to the lock-up solenoid. Output to.
[0117]
Note that the vehicle speed when the lockup release signal is output rather than the vehicle speed at the fuel recovery start timing (this vehicle speed is 40 km / h shown in FIG. 21) so that the lockup release signal is output before the fuel cover is performed. ) Is higher.
[0118]
When outputting the lockup signal, the flag FLU is set to "1" at step 73, and when outputting the lockup release signal, the FLU is reset to "0" at step 75. The value of the flag FLU is transmitted to the engine control control unit 20.
[0119]
Reference exampleIn FIG. 18, KGZ1 is shown in three stages of −0.75, −0.25, and 0, but is not limited to this, and the number of stages may be further increased. Further, it is not necessary to set a jump value (discontinuous value), and a continuous value may be used.
[0120]
Reference exampleIn the above description, KGZ1 ≦ 0.1As in the embodiment, torque can be increased by giving a positive value to KGZ1.
[0121]
In the embodiment, the case where the three gains Gztw, Gztwp, and Gztwm are values corresponding to the cooling water temperature Tw has been described. Thus, the present invention can be applied to a system in which three gains Gztw, Gztwp, and Gztwm are obtained.
[0122]
In the embodiment, the correction amount related to the slow-response wall flow fuel and the correction amount related to the fast-response wall flow fuel have been introduced. However, the correction amount related to the wall flow fuel is not limited to this, and other publicly known correction amounts may be used. The present invention can also be applied to those that perform wall flow fuel.
[Brief description of the drawings]
FIG. 1 is a control system diagram of a first embodiment.
FIG. 2 is a flowchart for explaining calculation of a cylinder-specific fuel injection pulse width Tin.
FIG. 3 is a characteristic diagram of a direct rate Z with respect to injection timing and cooling water temperature.
FIG. 4 is a flowchart for explaining calculation of three gains Gztw, Gztwp, and Gztwm.
FIG. 5 is a characteristic diagram of cylinder specific asynchronous injection gain Gztw.
FIG. 6 is a characteristic diagram of cylinder-by-cylinder increase gain Gztwp.
FIG. 7 is a characteristic diagram of a cylinder specific reduction gain Gztwm.
FIG. 8 is a flowchart executed at each injection timing.
FIG. 9 is a waveform diagram for explaining wall flow correction for high-frequency components of wall flow fuel during slow acceleration.
FIG. 10 is a waveform diagram for explaining wall flow correction for high-frequency components of wall flow fuel during rapid acceleration.
FIG. 11 is a flowchart for explaining determination of fuel recovery conditions.
FIG. 12 is a flowchart for explaining termination determination of a fuel recovery condition.
FIG. 13 is a waveform diagram for explaining wall flow correction for high frequency components of wall flow fuel during fuel recovery.
FIG. 14 is a flowchart for explaining calculation of a fuel recovery gain KGZ1;
FIG. 15 is a characteristic diagram of a fuel recovery gain KGZ1.
FIG. 16 together with the operation of the conventional deviceReference exampleIt is a wave form diagram for demonstrating the effect | action of.
FIG. 171It is a flowchart for demonstrating the calculation of the fuel recovery time gain KGZ1 of embodiment.
FIG. 181It is a characteristic view of gain KGZ1 and KGZ2 at the time of fuel recovery of embodiment.
FIG. 191It is a wave form chart at the time of fuel recovery of embodiment.
FIG. 201It is a flowchart for demonstrating determination of the lockup area | region of embodiment.
FIG. 211It is a characteristic view which shows the lockup area | region of embodiment.
FIG. 22 is a view corresponding to a claim of the first invention.
[Explanation of symbols]
1 engine
4 Fuel injection valve
7 Air flow meter
9 Throttle valve opening sensor
10 Crank angle sensor
20 Control unit

Claims (6)

Means for calculating a basic injection amount based on engine load and rotational speed;
Means for calculating an increase correction amount for wall flow fuel at the time of fuel recovery;
Means for calculating a fuel injection amount at the time of fuel recovery, a value obtained by correcting the basic injection amount by the increase correction amount;
In an air-fuel ratio control apparatus for an engine comprising means for supplying this amount of fuel to the engine,
Means for determining whether the vehicle speed has dropped and the fuel has been cut without depressing the accelerator pedal;
From this determination result, when the vehicle speed decreases without depressing the accelerator pedal and the fuel is cut, the increase correction amount increases as the amount of decrease in the rotational speed per predetermined period immediately before the fuel cover increases at the time of fuel recovery after the fuel cut. Rutotomoni provided with means for modifying the large side,
An air-fuel ratio control apparatus for an engine, wherein the increase correction amount is further increased when the rotational speed reduction amount per predetermined period is large and the automatic transmission is in a lockup region . The increase correction amount relating to the wall flow fuel is a first correction amount relating to the quickly responding wall flow fuel, and is a correction amount added to the basic injection amount that is an injection amount supplied in synchronization with engine rotation. The engine air-fuel ratio control apparatus according to claim 1. The air-fuel ratio control apparatus for an engine according to claim 2 , wherein temperature correction is performed on the first correction amount. 2. The increase correction amount related to the wall flow fuel is a second correction amount related to a fast response wall flow fuel, and is an asynchronous injection amount that is injected asynchronously with engine rotation during rapid acceleration. The engine air-fuel ratio control apparatus described. Means for calculating the basic injection amount for each cylinder as a synchronous injection amount to be supplied in synchronization with the engine rotation;
In order to save the first intake after the determination at the time of sudden acceleration, the amount of excessive injection by the asynchronous injection and the amount by which the wall flow is reduced by the port flow velocity in the first intake are predicted for each cylinder, and the asynchronous The engine air-fuel ratio control apparatus according to claim 4 , wherein a value obtained by subtracting the predicted value from the synchronous injection amount only at a synchronous injection timing that comes immediately after injection is calculated again as a synchronous injection amount for each cylinder. 6. The engine air-fuel ratio control apparatus according to claim 4, wherein temperature correction is performed on the asynchronous injection amount.

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